JP4409942B2 - Organic light-emitting device having a carrier transport layer containing a metal complex - Google Patents

Description

  This application claims the benefits of US Provisional Application No. 60 / 315,527, filed Aug. 29, 2001, and Application No. 60 / 317,541, filed Sep. 5, 2001. This application is related to co-pending US Provisional Application No. 60 / 317,540, filed on the same date, the entirety of which is incorporated herein by reference.

  The U.S. Government has paid licenses for the present invention and, in limited circumstances, grants licenses to others under reasonable terms and conditions set forth by the contract terms and numbers determined by DARPA. It shall have the rights required of the patentee.

  The present invention is directed to light emitting devices incorporating metal complexes with improved efficiency and stability.

  Electronic displays are currently the primary means for rapid information provision. Televisions, computer monitors, instrument display panels, calculators, printers, cell phones, handheld computers, etc. adequately demonstrate the speed, versatility and interactivity that is characteristic of this medium. Among the known electronic display technologies, organic light emitting devices (OLEDs) have been developed in the development of full-color flat panel display devices that can obscure the bulky cathode ray tubes still used today in many televisions and computer monitors. Is very interested in its potential role.

  In general, an OLED comprises a plurality of organic layers, at least one of which is made to exhibit electroluminescence by applying a voltage to the device (eg, Tang et al., Appl. Phys. Lett. 1987, 51, 913, and Burroughes et al., Nature, 1990, 347, 359). When a voltage is applied to the device, the cathode effectively reduces adjacent organic layers (ie, injects electrons) while the anode effectively oxidizes adjacent organic layers (ie, injects holes). Holes and electrons each move across the device toward the oppositely charged electrode. When holes and electrons meet on the same molecule, recombination occurs and excitons are formed. It is preferred that the recombination of holes and electrons is accompanied by emission of radiation, thereby resulting in electroluminescence.

  Depending on the spin state of holes and electrons, the exciton obtained by recombination of holes and electrons can have a triplet or singlet spin state. Luminescence from singlet excitons results in fluorescence, while luminescence from triplet excitons results in phosphorescence. For organic materials commonly used in OLEDs, statistically about a quarter of excitons are singlets and the remaining three quarters are triplets (eg, Baldo et al., Phys. Rev. B, 1999, 60, 14422). There are certain phosphorescent materials that can be used to make practical field phosphorescent OLEDs with a theoretical quantum efficiency of up to 100% (ie, harvesting both triplets and singlets). Until it was discovered, the most efficient OLEDs have generally been based on fluorescent materials. Since the transition to the ground state of the triplet is formally a spin-inhibited process, these materials have a theoretical quantum efficiency of up to 25% (where the quantum efficiency of an OLED is the efficiency of holes and electrons. Fluorescence occurs only when it recombines and generates luminescence). It has now been found that field phosphorescent OLEDs have superior overall device efficiency compared to electrofluorescent OLEDs (eg, Baldo et al., Nature, 1998, 395, 151 and Baldo, e.g., APPL.Phys.Lett.1999, Vol.75, No.3, p.4).

In general, an OLED includes a hole injection anode layer including an oxide material such as indium tin oxide (ITO), Zn—In—SnO ₂ , and SbO ₂ and a metal layer such as Mg, Mg: Ag, or LiF: Al. A plurality of thin organic layers are provided between the electron injection cathode layer. Due to its tendency to conduct positive charges (ie holes), the organic layer located close to the anode layer is usually referred to as the “hole transport layer” (HTL). Various compounds have been used as HTL materials. The most common materials consist of various triarylamines that exhibit high hole mobility. Similarly, due to its tendency to conduct negative charges (i.e. electrons), the organic layer located in close proximity to the cathode layer is referred to as an "electron transport layer" (ETL). Compared to HTL, the ETL materials used in OLEDs vary to some extent. A common ETL material is aluminum tris (8-hydroxyquinolate) (Alq ₃ ). ETL and HTL are often collectively referred to as a carrier layer. In some cases, additional layers may be present to enhance the injection of holes or electrons from the electrode to the HTL or ETL, respectively. These layers are often referred to as hole injection layers (HIL) or electron injection layers (EIL). HIL can be from small molecules such as 4,4 ′, 4 ″ -tris (30 methylphenylphenylamino) triphenylamine (MTDATA), or polymeric materials such as poly (3,4-ethylenedioxythiophene) (PEDOT). The EIL may be made of a small molecular material such as copper phthalocyanine (CuPc), and many OLEDs also have an emissive layer (EL) located between the ETL and the HTL, or in other words, With a luminescent layer where electroluminescence occurs, doping the emissive layer with a variety of emissive materials has made it possible to make OLEDs with a wide range of colors.

  In addition to the electrode, carrier layer, and light emitting layer, the OLED is also provided with one or more blocking layers that help maximize efficiency. These layers help to prevent holes, electrons and / or excitons from migrating and entering the inactive region of the device. For example, a blocking layer that confines holes in the emissive layer effectively increases the likelihood that the holes will be a light emitting event. The hole blocking layer desirably has a deep (ie, low) HOMO energy level (a characteristic of materials that are difficult to oxidize), while electron blocking materials generally have a high LUMO energy level. Exciton blocking materials have also been found to increase device efficiency. A relatively long-lived triplet exciton can move approximately 1500-2000 mm, and this distance may be greater than the overall device width. An exciton blocking layer comprising a material featuring a wide band gap can help prevent exciton loss to non-emitting regions of the device.

  In search of higher efficiency, devices having layers containing luminescent metal complexes have been experimentally fabricated. A functional OLED having a light-emitting layer made of tris (2,2 ';-bipyridine) ruthenium (II) complex or a polymer derivative thereof is disclosed in Gao et al. Am. Chem. Soc. 2000, 122, 7426, Wu et al., J. MoI. Am. Chem. Soc. 1999, 121, 4883, Lyons et al., J. MoI. Am. Chem. Soc. 1998, 120, 12100, Elliot et al., J. MoI. Am. Chem. Soc. 1998, 120, 6781 and Maness et al., J. MoI. Am. Chem. Soc. 1997, Vol. 119, page 3987. Luminescent materials containing iridium-based metals and other metals are described in, for example, Baldo et al., Nature, 1998, 395, 151; Baldo et al., Appl. Phys. Lett. 1999, 75, 4; Adachi et al., Appl. Phys. Lett. 2000, 77, 904; Adachi et al., Appl. Phys. Lett. 2001, 78, 1622; Adachi et al., Bull. Am. Phys. Soc. 2001, 46, 863, Wang et al., Appl. Phys. Lett. 2001, 79, 449 and U.S. Pat. Nos. 6,030,715, 6,045,930 and 6,048,630. A light emitting layer containing a (5-hydroxy) quinoxaline metal complex as a host material is also described in US Pat. No. 5,861,219. Efficient multicolor devices and displays are also described in US Pat. No. 5,294,870 and International Patent Application No. WO 98/06242.

  Metal containing blocking layers have also been reported. Specifically, Watanabe et al., “Optimization of driving lifetime in organic LED devices using Ir complex”, edited by Kafafi Materials and Devices of Organic Light Emitting. IV (Organic Light Emitting Materials and Devices IV) ", Proceedings of SPIE, Vol. 4105, 175 (2001), (1,1'-biphenyl) -4-olato) bis (2-methyl-8- Quinolinolato N1, O8) aluminum (BAlq) has been used as a blocking layer in OLEDs.

  Although OLEDs have been promised as new technologies in electronic displays, degradation, short lifetime, and loss of efficiency over time are often problematic. The organic layer can be irreversibly damaged by constant exposure to the high temperatures normally experienced by the device. A number of oxidation and reduction events can also cause damage to the organic layer.

Therefore, there is a need to develop new materials for making OLEDs. A compound that is stable to both oxidation and reduction, has a high _Tg value, and easily forms a glassy thin film is desirable. The invention described below helps to realize these and other needs.

  The present invention provides a light emitting device comprising a hole transport layer comprising at least one metal complex. In some embodiments, the hole transport layer consists essentially of one or more of the metal complexes. In another embodiment, the hole transport layer comprises an organic matrix doped with one or more of the metal complexes.

  In some embodiments, the metal complex is coordinately saturated, preferably the metal complex has a coordination number of 4 or 6. In some embodiments, the metal of the metal complex is a transition metal that may be a first, second, or third series of transition metals. In some embodiments, the metal of the metal complex is Fe, Co, Ru, Pd, Os or Ir, or any sub-combination thereof.

［式中、Ｍ’及びＭ’’’はそれぞれ独立に金属原子であり、
Ｒ_１０、Ｒ_１３、Ｒ_２０及びＲ_２１はそれぞれ独立にＮ又はＣであり、
Ｒ_１１及びＲ_１２はそれぞれ独立にＮ又はＣであり、
環系Ａ、Ｂ、Ｇ、Ｋ及びＬはそれぞれ独立に、任意選択で最大５個のヘテロ原子を含む単環、二環もしくは三環の縮合脂肪族又は芳香族環系であり、
ＺはＣ_１〜Ｃ_６アルキル、Ｃ_２〜Ｃ_８モノ−もしくはポリアルケニル、Ｃ_２〜Ｃ_８モノ−もしくはポリアルキニル、又は結合であり、
ＱはＢＨ、Ｎ又はＣＨである］
In some embodiments of the light emitting device of the present invention, the at least one metal complex has one of Formula I or II.

[Wherein, M ′ and M ′ ″ are each independently a metal atom,
R ₁₀ , R ₁₃ , R ₂₀ and R ₂₁ are each independently N or C ;
R ₁₁ and R ₁₂ are each independently N or C ;
Ring systems A, B, G, K and L are each independently monocyclic, bicyclic or tricyclic fused aliphatic or aromatic ring systems optionally containing up to 5 heteroatoms;
Z is _C 1 -C _{6 alkyl,} C 2 -C ₈ mono - and or polyalkynyl, or a bond, - or _polyalkenyl, C 2 -C ₈ mono
Q is BH, N or CH]

  In some embodiments, the metal complex has Formula I, and ring system A and ring system B are each monocyclic. In other embodiments, the metal complex has Formula I, ring system A is a 5-membered heteroaryl monocycle, and ring system B is a 6-membered aryl or heteroaryl monocycle.

In some other embodiments, R ₁₀ and R ₁₁ are N and R ₁₃ is CH. In other embodiments, Ring A forms a pyrazole. In yet other embodiments, Ring B forms phenyl.

In some embodiments of the light emitting device of the present invention, the metal of the at least one metal complex is a d ⁰ , d ¹ , d ² , d ³ , d ⁴ , d ⁵ or d ⁶ metal. In some embodiments where the metal complex has Formula I, M ′ is a transition metal. In other embodiments, M ′ is Fe, Co, Ru, Pd, Os, or Ir. In other embodiments, M ′ is Fe or Co. In other embodiments, M ′ is Fe, and in yet other embodiments, M ′ is Co.

In some embodiments of the light-emitting devices of the present invention where the metal complex has Formula I, the metal complex is Co (ppz) ₃ .

In some embodiments of the light emitting device of the present invention, the at least one metal complex has the formula II. In some embodiments of the light emitting device of the invention, wherein the at least one metal complex has the formula II, the ring systems G, K and L are each a 5-membered or 6-membered monocycle. In other embodiments, ring systems G, K are each a 5-membered heteroaryl monocycle. In still other embodiments, R ₂₁ and R ₂₂ are each N.

In another embodiment of the light emitting device of the invention, wherein the at least one metal complex has the formula II, the ring systems G, K and L each form a pyrazole. In other embodiments, M ′ ″ is a d ^5/6 or d ^2/3 metal.

  In some embodiments of the light emitting device of the present invention, wherein at least one metal complex has the formula II, M '' 'is a transition metal. In other embodiments, M "" is Fe, Co, Ru, Pd, Os, or Ir. In other embodiments, M "" is Fe or Co. In other embodiments, M "" is Fe.

Metal complexes in some embodiments is FeTp _'2.

  In some embodiments of the light emitting device of the present invention, the light emitting device further comprises an electron blocking layer that can include an organic electron blocking material, a metal complex, or both. In some embodiments, the organic electron blocking material is selected from triarylamine or benzylidene. In some embodiments, the electron blocking layer consists essentially of a metal complex. In another embodiment, the electron blocking layer comprises a matrix doped with the metal complex.

  In some embodiments, the electron blocking layer has a HOMO energy level that approximates the HOMO energy level of the hole transport layer. In another embodiment, the electron blocking layer has a HOMO energy level that is higher than the HOMO energy level of the hole transport layer.

  In some embodiments, the metal complex of the electron blocking layer comprises a metal selected from Ga, In, Sn, or a group 8, 9, or 10 transition metal. In some embodiments, the metal complex of the electron blocking layer comprises Ga. In other embodiments, the metal complex of the electron blocking layer comprises a multidentate ligand. In some embodiments, the polydentate ligand has a bridging atom selected from N and P. In other embodiments, the polydentate ligand has a mesityl bridging moiety. In other embodiments, the polydentate ligand comprises up to 3 monocyclic, bicyclic, or tricyclic heteroaromatic moieties.

［式中、
Ｍは金属原子であり、
ＸはＮ又はＣＸ’（式中、Ｘ’はＨ、Ｃ_１〜Ｃ_２０アルキル、Ｃ_２〜Ｃ_４０モノ−もしくはポリアルケニル、Ｃ_２〜Ｃ_４０モノ−もしくはポリアルキニル、Ｃ_３〜Ｃ_８シクロアルキル、アリール、ヘテロアリール、アラルキル、ヘテロアラルキル、又はハロである）であり、
ＡはＣＨ、ＣＸ’、Ｎ、Ｐ、Ｐ（＝Ｏ）、アリール又はヘテロアリールであり、
Ｒ^１及びＲ^２はそれぞれ独立に、Ｈ、Ｃ_１〜Ｃ_２０アルキル、Ｃ_２〜Ｃ_４０アルケニル、Ｃ_２〜Ｃ_４０アルキニル、Ｃ_３〜Ｃ_８シクロアルキル、アリール、アラルキル、又はハロである、又は
Ｒ^１及びＲ^２は、これらを結合している炭素原子と共に、連結して縮合したＣ_３〜Ｃ_８シクロアルキル又はアリール基を形成し、
Ｒ^３はＨ、Ｃ_１〜Ｃ_２０アルキル、Ｃ_２〜Ｃ_４０アルケニル、Ｃ_２〜Ｃ_４０アルキニル、Ｃ_３〜Ｃ_８シクロアルキル、アリール、アラルキル、又はハロであり、
ｎは１〜５である］
を有する化合物を含む。 In some embodiments of the light emitting device of the present invention, the electron blocking layer is of formula III

[Where:
M is a metal atom,
X is N or CX ′ where X ′ is H, C ₁ -C ₂₀ alkyl, C ₂ -C ₄₀ mono- or polyalkenyl, C ₂ -C ₄₀ mono- or polyalkynyl, C ₃ -C ₈ cyclo Alkyl, aryl, heteroaryl, aralkyl, heteroaralkyl, or halo),
A is CH, CX ′, N, P, P (═O), aryl or heteroaryl,
R ¹ and R ² are each independently H, C ₁ -C ₂₀ alkyl, C ₂ -C ₄₀ alkenyl, C ₂ -C ₄₀ alkynyl, C ₃ -C ₈ cycloalkyl, aryl, aralkyl, or halo. Or R ¹ and R ² together with the carbon atom bonding them together form a fused C ₃ -C ₈ cycloalkyl or aryl group;
R ³ is H, C ₁ -C ₂₀ alkyl, C ₂ -C ₄₀ alkenyl, C ₂ -C ₄₀ alkynyl, C ₃ -C ₈ cycloalkyl, aryl, aralkyl, or halo;
n is 1-5]
A compound having

In some embodiments where the electron blocking layer has Formula III, M is a trivalent metal atom, X is CH or N, A is N or 1,3,5-phenyl, R ¹ and R ² is each H, or R ¹ and R ² are joined together with the carbon atom to which they are linked to form a phenyl group, R ³ is H and n is 1 or 2. In other embodiments where the electron blocking layer has Formula III, M is Ga.

In other embodiments, the electron blocking layer comprises Ga (pma) ₃ .

In some embodiments of the light emitting device of the present invention, the metal complex of the hole transport layer is Co (ppz) ₃ . In another embodiment of the light-emitting device of the present invention, metal complexes of the HTL is FeTp _'2.

In another embodiment of the light emitting device of the invention, the electron blocking layer comprises Ga (pma) ₃ and the metal complex of the hole transport layer is Co (ppz) ₃ .

In another embodiment of the light emitting device of the present invention, the electron blocking layer comprises Ga (pma) ₃ , and the metal complex of the hole transport layer is FeTp ′ ₂ .

  The present invention also provides a light emitting device including a partial structure HTL / EL or HTL / EBL / EL in which each of the EL, HTL, and EBL includes at least one metal complex.

  The present invention also provides a light emitting device comprising a partial structure HTL / EL or HTL / EBL / EL, wherein none of the EL, HTL or EBL consists of organic molecules.

  The present invention further provides a light-emitting device having a plurality of layers, which does not include a layer consisting only of organic molecules. In some embodiments, each of the layers contains at least one metal complex.

The present invention is a light emitting device comprising a hole transport layer, a light emitting layer and a blocking layer,
The hole transport layer has a first HOMO energy, the hole transport layer comprises at least one metal complex;
The emissive layer includes at least one material capable of transporting electrons, the material has a second HOMO energy, and the blocking layer has a HOMO energy between the first and second HOMO energies. A device comprising the material having is also provided.

  In some embodiments, a blocking layer is present between the hole transport layer and the light emitting layer. In other embodiments, but not necessarily, the blocking layer comprises an organic electron blocking material that can be selected from triarylamine or benzylidene. In still other embodiments, the electron blocking layer comprises a metal complex.

  The present invention is a method for facilitating hole transport in a light emitting device, wherein the light emitting device comprises a hole transport layer and a light emitting layer, the hole transport layer comprising at least one metal complex, and The method wherein the light emitting layer comprises at least one material capable of transporting electrons, the material having a second HOMO energy higher than the HOMO energy of the hole transport layer; Disposing a blocking layer between the hole transport layer and the light emitting layer, wherein the blocking layer comprises a material having a HOMO energy level that is intermediate between the first and second HOMO energies. Also provide.

In some embodiments of the above method, the metal complex of the hole transport layer is a complex of the above formula I or II. In some embodiments, the metal complex of the hole transport layer is Co (ppz) ₃ or FeTp ′ ₂ . In other embodiments, the blocking layer comprises at least one metal complex. In some embodiments, the metal complex of the blocking layer is a compound having Formula III above. In other embodiments, the metal complex of the blocking layer is Ga (pma) ₃ . In another embodiment, the hole transport layer comprises Co (ppz) ₃ or FeTp ′ ₂ and the barrier layer comprises Ga (pma) ₃ .

The present invention is a method of making a light emitting device, the method comprising disposing a hole transport layer in electrical contact with the light emitting layer, wherein the hole transport layer is of formula I or II above. Also provided are methods comprising the compounds of: In some embodiments, the light emitting device further includes an electron blocking layer. In other embodiments, the electron blocking layer comprises a compound having Formula III above. In other embodiments, the electron blocking layer comprises Ga (pma) ₃ . In another embodiment, the compound is a compound of Formula I, and a Co _{(ppz) 3} or FeTp _'2. In other embodiments, the compound is also Co (ppz) ₃ .

  The present invention is also a method for transporting holes in a hole transport layer of a light emitting device, wherein the hole transport layer includes at least one metal complex, and the method applies a voltage to the device. A method is also provided.

  The present invention also provides pixels and displays comprising the devices described herein.

BEST MODE FOR CARRYING OUT THE INVENTION

  In this specification, with respect to molecular orbital energy, the terms “low” and “deep” are used interchangeably. Lower and deeper generally indicates that the molecular orbitals are lower, i.e., at a more stable energy level. Electron ionization from deeper orbits is shallower, that is, requires more energy than electron ionization in higher orbitals. Thus, deeper trajectories are referred to as lower, but these are often numerically represented by larger numbers. For example, a molecular orbital located at 5.5 eV is lower (deeper) than a molecular orbital located at 2.5 eV. Similarly, with respect to orbital energy levels, the terms “shallow” and “high” refer to trajectories with less stable energy levels. These terms are well known to those skilled in the art.

  As used herein, the term “adjacent” refers to a layer having side surfaces that are in contact with the layer of the light emitting device. For example, a first layer and a second layer adjacent to each other represent, for example, contacted layers in which one side of one layer is in contact with one side of the other layer.

  As used herein, the term “gap” or “band gap” generally refers to the difference in energy, eg, between HOMO and LUMO. “Wider gap” refers to a greater energy difference than “narrower gap” or “smaller gap”. “Carrier gap” represents the energy difference between the HOMO and LUMO of the carrier.

  The present invention is particularly directed to light emitting devices comprising one or more layers containing at least one metal complex. Such devices can have higher efficiency and higher stability compared to devices with conventional organic blocking layers.

  The light emitting device of the present invention is generally a laminated structure that exhibits electroluminescence when a voltage is applied to the device. A typical device is constructed such that one or more layers are sandwiched between a hole injection anode layer and an electron injection cathode layer. The sandwiched layer has two sides, one facing the anode and the other facing the cathode. These side surfaces are referred to as the anode side and the cathode side, respectively. The layer is typically deposited on a substrate such as glass. There may be either an anode layer or a cathode layer on the substrate. In some embodiments, the anode layer is in contact with the substrate. In many cases, an insulating material can be inserted between the electrode layer and the substrate, for example when the substrate comprises a conductor or semiconductor material. Common substrate materials may be rigid, flexible, transparent or opaque, including glass, polymer, quartz, sapphire and the like.

In order to facilitate the transport of electrons, a hole transport layer is disposed adjacent to the anode layer. In some embodiments, a hole injection layer for enhancing hole injection, sometimes referred to as a hole injection enhancement layer, is disposed between and adjacent to the anode and the HTL. Can do. Suitable materials for HTL include any material that functions as known to those skilled in the art. Suitable materials are generally easy to oxidize and are N, N′-diphenyl-N, N′-bis (3-methylphenyl) 1-1′biphenyl-4,4′diamine (TPD), 4,4 ′. -Bis [N- (I-naphthyl) -N-phenyl-amino] biphenyl (α-NPD), 4,4′-bis [N- (2-naphthyl) -N-phenyl-amino] biphenyl (β-NPD) And triarylamines such as Metal complexes can also be used for HTL. Several suitable metal complexes are described, for example, in application 60 / 283,814 filed April 13, 2001, which is hereby incorporated by reference in its entirety. Similarly, the ETL is placed adjacent to the cathode layer to facilitate electron transport. An electron injection enhancement layer can optionally be placed adjacent to the ETL or cathode layer. Suitable materials for ETL include any material having such a function known to those skilled in the art. Typical ETL materials are relatively easy to reduce and include, for example, aluminum tris (8-hydroxyquinolate) (Alq ₃ ), carbazole, oxadiazole, triazole, thiophene, oligothiophene, and the like. The HTL and ETL carrier layers can have a thickness of about 100 to about 1000 mm. The EL layer is preferably somewhere between HTL and ETL since it is generally the exciton production and emission part. The EL may optionally be in contact with one or both of the HTL and ETL, or may be lined with one or more blocking layers. The EL material may include, for example, Alq ₃ doped with a dye. In some embodiments, a film of emissive material with nothing added (undoped) can be used as the emissive layer. Furthermore, the layer can serve a dual function. For example, ETL or HTL can also function as an EL.

  In some embodiments according to the present invention, the device comprises at least one charge transport layer (ie carrier layer) containing at least one metal complex, such as an HTL, ETL, hole injection layer or electron injection layer. Including. The carrier layer may be a thin film consisting essentially of a metal complex or an organic matrix doped with a metal complex. In some preferred embodiments, the devices of the present invention include a hole blocking layer containing at least one metal complex. Thus, in some embodiments, a metal complex of HTL can be selected whose HOMO energy level assists hole transport. That is, in some embodiments, it is preferred to select a metal complex having a HOMO energy level in the range of about 7 to 4.5 eV and a LUMO energy level in the range of about 2 to about 4 eV.

  Based on the property of facilitating this function, a metal complex suitable for the charge transport layer used in the device can be selected. For example, hole transport materials generally undergo one-electron oxidation. Thus, metal complexes that are stable to one-electron oxidation processes can be suitable as hole transporters. Similarly, metal complexes that are stable to one-electron reduction may be suitable as electron transport materials. The stable oxidation and reduction process can be further confirmed by an electrochemical method such as cyclic voltammetry described later. Another consideration is charge mobility. For example, a material having high hole mobility can generally function as a good hole transporter. Charge mobility often corresponds to the low reorganization energy (ies) of the redox process. Thus, for example, metal complexes that show little structural difference when oxidized or reduced generally have a relatively low energy barrier (re-formulation energy) associated with oxidation or reduction. As is well known in the art and as described below, certain metal properties, such as electronic configuration, can affect the recombination barrier. In addition, certain ligand properties, such as coordination conformity, can affect the recombination barrier of redox events in metal complexes, details of which are further discussed below.

  In some embodiments, it may be desirable for one or more layers of the device to include one or more dopants. In order to improve efficiency and color tunability, a luminescent dopant (ie light emitting molecule, luminescent material) can be included in at least one layer such as EL. Doped layers typically contain a majority of the host material and a minor portion of the dopant. The host material (also referred to as the matrix) generally transports excitons to the emissive dopant material via a non-radioactive process, which then emits light of the wavelength characteristics of the dopant rather than the host.

  The dopant also serves to trap charge. For example, the LUMO level of the host and dopant can be adjusted so that the LUMO level of the dopant is lower than the LUMO level of the host, so that the dopant molecules can act as electron traps. Similarly, the HOMO levels of the host and dopant can be adjusted so that the HOMO level of the dopant is higher than the HOMO level of the host, so that the dopant molecules act as hole traps. One or more dopants, referred to as transport dopants, can be used to facilitate energy transport from the host to the luminescent dopant. For example, cascade doping can be used that causes non-radioactive transport of excitons from the host molecule to the luminescent dopant through one or more transport dopants. These intermediate transports may be by Forster transport, Dexter transport, hole trapping or electron trapping, resulting in the formation of excitons with transport or luminescent dopants, or as appropriate Any other mechanism may be used.

  The dopant may be present in the host material in an amount ranging, for example, from about 0.1 to about 50%, from about 1 to about 20%, or from 1 to about 10% by weight. The light emitting dopant in the host material is preferably doped at a level of about 1% by weight. Alternatively, in some embodiments, the level of dopant is about the average intermolecular distance between dopant molecules that is about the dopant's Forster radius, eg, about 20 to about 40 cm or about 25 to about 35 mm, or about 30 mm. As a result. The luminescent dopant includes any compound capable of emitting light. Luminescent dopants include fluorescent organic dyes known in the art such as laser dyes. Preferred emissive dopants include application 08 / 980,986, filed Dec. 1, 1997, application 09 / 883,734, filed Jun. 18, 2001, and application 60/98, filed Apr. 13, 2001. Included are phosphorescent metal complexes such as Ir, Pt and other heavy metal complexes disclosed in US Pat. No. 283,814. Each of which is incorporated herein by reference in its entirety.

  In some embodiments, the device of the present invention includes at least one blocking layer. The blocking layer (BL) functions to confine holes, electrons and / or excitons to specific regions of the light emitting device. For example, device efficiency can be increased if excitons are confined to the EL and / or if holes and electrons are prevented from moving from the EL. The blocking layer can serve one or more blocking functions. For example, the hole blocking layer can also serve as an exciton blocking layer. In some embodiments, in the device of the present invention, the hole blocking layer does not simultaneously act as a light emitting layer. The blocking layer can comprise a compound that is capable of emission, but the emission can occur in a separate light emitting layer. Thus, in a preferred embodiment, the blocking layer does not exhibit luminescence. The blocking layer can be thinner than the carrier layer. Typical blocking layers have a thickness in the range of about 50 to about 1000 inches, or about 50 to about 750 inches, or about 50 to about 500 inches. Furthermore, the blocking layer preferably contains a compound other than BAlq.

  The hole blocking layer (HBL) generally includes a material that is difficult to acquire holes. For example, hole blocking materials are relatively difficult to oxidize. In most cases, hole blocking materials are less susceptible to oxidation from transport holes than adjacent layers. Materials that are more difficult to oxidize than other materials generally have lower HOMO energy levels. For example, by placing a blocking layer of material adjacent to the EL on the cathode side of the device, holes generated from the anode and moving to the EL are effectively blocked from exciting the EL (on the cathode side). be able to. The blocking layer preferably has a HOMO energy level that is lower than the HOMO energy level of the EL. A large difference in HOMO energy level corresponds to better hole blocking capability. The HOMO of the blocking layer material is preferably at least about 50, 100, 200, 300, 400, 500 meV (millielectron volts), or deeper than the HOMO level of the adjacent layer in which holes are confined. In some embodiments, the HOMO of the blocking layer material is at least about 200 meV deeper than the HOMO level of the adjacent layer in which holes are confined.

  In some devices of the present invention, the layer in which holes are confined can include more than one material, such as a host material (matrix) and a dopant. In this case, the HBL preferably has a lower (deeper) HOMO energy level than the adjacent layer material (ie, the material with the highest (shallowest) HOMO energy level) that carries the majority of the positive charge. For example, the emissive layer can include a host material having a HOMO energy level deeper than the dopant. In this case, the dopant acts as a trap for holes and can be the main hole transporter of the light emitting layer. Accordingly, in such embodiments, the HOMO energy of the dopant is taken into account when selecting the hole blocking layer. Thus, in some embodiments, the HOMO energy level of the HBL may be higher than the host material and lower than the dopant level.

  The hole blocking layer is also preferably a good electron injector. Therefore, the LUMO energy level of HBL is preferably close to the LUMO energy level of the layer in which holes are confined. In some embodiments, the difference in LUMO energy level between the two layers may be about 500 meV, 200 meV, 100 meV, less than 50 meV, or less. Hole blocking layers, which are also good electron injectors, generally have a lower energy barrier to electron injection than to hole leakage. Thus, the difference in LUMO energy between the HBL and the layer in which holes are confined (corresponding to the electron injection energy barrier) is less than their HOMO energy difference (ie hole blocking energy barrier).

  Conversely, the electron blocking layer (EBL) includes a material that is difficult to acquire electrons (that is, relatively difficult to reduce). In terms of a light-emitting device, EBL is preferably less likely to be reduced than an adjacent layer in which electrons move. Materials that are less likely to reduce than other materials generally have higher LUMO energy levels. As an example, by disposing an adjacent blocking layer on the anode side of the EL where the blocking layer has a LUMO energy level higher than the EL's LUMO energy level, electrons generated from the cathode and transferred to the EL layer excite the EL. Can be prevented (on the anode side). A larger difference in LUMO energy level corresponds to better electron blocking capability. The LUMO of the blocking layer material is preferably at least about 50 meV, 100 meV, 200 meV, 300 meV, 400 meV, 500 meV, or more (shallow) than the LUMO level of the adjacent layer where the holes are confined. In some embodiments, the LUMO of the blocking layer material may be at least about 200 meV higher (shallow) than the LUMO level of the adjacent layer in which holes are confined.

  In some embodiments, the layer in which electrons are confined can include more than one material, such as a host material (matrix) and a dopant. In this case, the EBL preferably has a higher LUMO energy level than the material of the adjacent layer (eg, the host or dopant having the lowest LUMO energy level) that carries the majority of the negative charge. For example, the emissive layer can include a host material having a LUMO energy level deeper than the dopant. In this case, the host may be the main electron transporter of the light emitting layer. In such an embodiment, the LUBL energy level of the EBL may be higher than the host material and lower than the dopant level. Similarly, the EBL preferably has a higher LUMO than the dopant when the dopant serves as the primary carrier of electrons.

  The electron blocking layer is also preferably a good hole injector. Therefore, the HOMO energy level of EBL is preferably close to the HOMO energy level of the layer in which electrons are confined. In some embodiments, the difference in the HOMO energy level between the two layers may be about 500 meV, 200 meV, 100 meV, less than 50 meV, or less. Electron blocking layers that are also good hole injectors generally have a smaller energy barrier to hole injection than to electron leakage. Thus, the HOMO energy difference between the EBL and the layer in which electrons are confined (corresponding to a hole injection energy barrier) is smaller than these LUMO energy differences (eg, an electron blocking energy barrier).

  Exciton migration from the EL to other parts of the device can be blocked by materials that are difficult to acquire excitons. If the receiving material has a wider (larger) optical gap than the material providing the excitons, exciton migration from one material to the other can be prevented. For example, by placing an exciton blocking layer adjacent to the EL layer that has a wider optical gap than the material comprising the EL layer, the exciton can be substantially confined to the EL layer of the device. The exciton blocking layer may be disposed on either side of the EL. Depending on the HOMO or LUMO energy level of the exciton blocking material compared to that of the adjacent layer, the exciton blocking layer can also act as HBL or EBL (as discussed above). Furthermore, if either the HOMO energy level or the LUMO energy level of the exciton blocking layer is energetically approximated to the respective HOMO energy level or LUMO energy level of the adjacent layer, the exciton blocking layer is a good electron or It can be a hole injector. For example, in a device having an exciton blocking layer and a light emitting layer, the exciton blocking layer can have a HOMO energy level that is about 500, 200, or 100 meV lower than the HOMO energy level of the light emitting layer. Conversely, the exciton blocking layer may have a LUMO energy level that is about 500, 200, 100 meV lower than the LUMO energy level of the light emitting layer.

According to some embodiments of the invention, the blocking layer can also include a dopant. As an example, the blocking layer can be composed of a wide band gap matrix (host) material doped with less band gap dopant. Depending on the combination of matrix and dopant, the presence of the dopant can reduce the effective LUMO energy of the blocking layer, thereby improving the electron conductivity and injection properties of the hole blocking layer. Conversely, the presence of the dopant can increase the effective HOMO energy of the blocking layer, thereby improving the hole injection characteristics. For example, in some embodiments, the HBL includes a wide band gap matrix doped with a smaller band gap material, where the deep HOMO energy level of the matrix serves to prevent hole transport. The relatively shallow LUMO level of the dopant favors electron injection. In some embodiments of the invention, the matrix is substantially conjugated such as octaphenylcyclooctatetraene (OPCOT), oligophenylenes such as hexaphenyl, and other similar materials having a wide band gap. Can contain organic molecules. A suitable matrix band gap value may be at least about 3 eV, but may be at least about 2.5 eV, 3.0 eV, 3.3 eV, 3.5 eV, or more. The dopant is preferably a metal complex. The doping level may range from about 1 to about 50%, more preferably from about 5 to about 20%, and even more preferably from about 10 to about 15% by weight. An example of a suitable metal complex used as a dopant for the blocking layer is bis (2- (4,6-difluorophenyl) pyridyl-N, C2 ′) iridium (III) picolinate (FIrpic). An example of a hole blocking layer comprising a matrix doped with a metal complex is OPCOT doped with 15 wt% FIrpic (OPCOT: FIrpic (15%)). For example, OPCOT: FIrpic has a lower HOMO of OPCOT than that of Irppy and a higher LUMO of FIrpic than that of CBP, so Ir (ppy) ₃ (tris (2-phenylpyridyl-N, C2 ′) iridium (III) , Irppy), holes can be effectively confined in the light emitting layer containing CBP doped.

Metal complexes used in the devices of the present invention include metal coordination complexes containing at least one metal atom and at least one ligand. Metal complexes may be charged or uncharged, but uncharged complexes are amenable to thin film deposition techniques used in OLED fabrication. The metal complex is preferably stable to both one-electron oxidation and one-electron reduction processes. Redox stable complexes can be identified, for example, by cyclic voltammetry (eg, identification of reversible redox events). In addition, such metal complexes often have low recombination energy barriers associated with oxidation and reduction. Thus, complexes with low recombination energy barriers show little structural difference between dormant, oxidized and reduced states. In general, metal complexes characterized by having a low recombination energy barrier include complexes having electronic configurations of d ⁰ , d ¹ , d ² , d ³ , d ⁴ , d ⁵ and d ⁶ . For example, octahedral complexes having d ³ or d ⁶ metals typically have a generally low re energy barriers. Since there is little structural change in the ligand set upon oxidation or reduction, metal complexes in which redox events predominantly affect unbound molecular orbitals (such as the t _2g set in octahedral transition metal complexes) Generally it has a low re-blend energy barrier. The recombination energy associated with a redox event can also be adjusted by the ligand set. For example, polydentate ligands in metal complexes structurally impose some kind of coordination geometry. Relatively inflexible ligands such as tridentate, tetradentate and hexadentate can constrain the coordination geometry so that redox events do not result in significant structural recombination. Also preferred are coordinately saturated metal complexes such as hexacoordination complexes that are unlikely to cause significant structural changes associated with oxidation or reduction. Tetracoordination complexes are also suitable and can include tetrahedral and planar square complexes and others. Octahedral complexes are also suitable because they tend to form glassy films. Metal complexes containing aromatic ligands can preferably help facilitate the redox process when redox events are largely concentrated in the ligand. Furthermore, due to its higher thermal stability, metal complexes containing heavy metals are preferred over those having lighter metals. For example, complexes containing second and third series transition metals are preferred.

  Typically, any metal atom, including transition metals, lanthanides, actinides, alkaline earths and alkali metals, is suitable for metal complexes in any available oxidation state. Transition metals include Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, Hf, Ta, W , Re, Os, Ir, Pt, Au, and Hg. Typical metals include Al, Ga, Ge, In, Sn, Sb, Tl, Pb, Bi and Po. In some embodiments, metals having an atomic number greater than about 13, 36, or 54 are preferred.

  The metal complex can include any suitable ligand system. Suitable ligands may be monodentate, bidentate, multidentate, π-bonded, organic, inorganic, charged, uncharged types. Furthermore, the ligand preferably contains one or more heteroatoms through which the metal atom is coordinated, but organometallic compounds containing coordinating carbons are also suitable, which are also metal complexes and Conceivable. The coordination heteroatom of the ligand may include oxygen, nitrogen, sulfur, phosphorus and the like. Nitrogen-containing ligands include amines, nitrenes, azides, diazenes, triazenes, nitric oxide, polypyrazolyl borate, 2,2'-bipyridine (bpy), 1,10-phenanthroline, terpyridine (trpy), pyridazine, Heterocycles such as pyrimidines, purines, pyrazines, pyridines, 1,8-naphthyridines, pyrazolates, imidazolates, and macrocycles with and without a conjugated π-system can be included. Phosphorus-containing ligands generally include phosphine and the like. Oxygen-containing ligands include water, hydroxide, oxo, superoxide, peroxide, alkoxide, alcohol, aryl oxide, ether, ketone, ester, carboxylate, crown ether, β-diketone, carbamate, dimethyl Contains sulfoxide and oxoanions such as carbonate, nitrate, nitrite, sulfate, sulfite, phosphate, perchlorate, molybdate, tungstate, oxalate and related groups It is. Sulfur-containing ligands can include hydrogen sulfide, thiols, thiolates, sulfides, disulfides, thioethers, sulfur dioxide, dithiocarbamates, 1,2-dithiolenes, and the like. Ligands containing coordinating carbon atoms can include cyanides, carbon disulfides, alkyls, alkenes, alkynes, carbides, cyclopentadienides, and the like. Halides can also act as ligands. Metal complexes containing these and other ligands are described in detail in Cotton and Wilkinson, Advanced Inorganic Chemistry, 4th edition, John Wiley & Sons, New York, 1980. The entirety of which is incorporated herein by reference. Other suitable ligands are described in application 60 / 283,814 filed April 13, 2001 and 09 / 883,734 filed June 18, 2001. Each of which is incorporated herein by reference in its entirety.

  In order to neutralize, in whole or in part, any positive formal charge associated with the metal atom of the metal complex, the ligand, in particular the neutral ligand, further comprises one or more anionic groups. It may be derivatized with a substituent. Suitable anionic substituents can include carbonates, nitrates, nitrites, sulfates, sulfites, phosphates, and the like.

  Examples of metal complexes suitable for use in the hole transport layer include, among others, transition metal complexes having a first, second or third series of transition metals including, for example, Fe, Co, Ru, Pd, Os and Ir Etc. are included. Other examples include coordination-saturated complexes and hexacoordinate or tetracoordinate complexes.

［式中、Ｍ’及びＭ’’’はそれぞれ独立に金属原子であり、
Ｒ_１０、Ｒ_１３、Ｒ_２０及びＲ_２１はそれぞれ独立にＮ又はＣであり、
Ｒ_１１及びＲ_１２はそれぞれ独立にＮ又はＣであり、
環系Ａ、Ｂ、Ｇ、Ｋ及びＬはそれぞれ独立に、任意選択で最大５個のヘテロ原子を含む単環、二環もしくは三環の縮合脂肪族又は芳香族環系であり、
ＺはＣ_１〜Ｃ_６アルキル、Ｃ_２〜Ｃ_８モノ−もしくはポリアルケニル、Ｃ_２〜Ｃ_８モノ−もしくはポリアルキニル、又は結合であり、
ＱはＢＨ、Ｎ又はＣＨである］
を含む正孔阻止層を含む。 In some embodiments of the invention, the device comprises at least one metal complex of formula I or II

[Wherein, M ′ and M ′ ″ are each independently a metal atom,
R ₁₀ , R ₁₃ , R ₂₀ and R ₂₁ are each independently N or C ;
R ₁₁ and R ₁₂ are each independently N or C ;
Ring systems A, B, G, K and L are each independently monocyclic, bicyclic or tricyclic fused aliphatic or aromatic ring systems optionally containing up to 5 heteroatoms;
Z is _C 1 -C _{6 alkyl,} C 2 -C ₈ mono - and or polyalkynyl, or a bond, - or _polyalkenyl, C 2 -C ₈ mono
Q is BH, N or CH]
Including a hole blocking layer.

A particularly preferred compound of formula I is Co (ppz) ₃ whose structure is shown below.

A particularly suitable other compound of the above formula II is iron trispirazolylborate (FeTp ′ ₂ ), the structure of which is shown below.

  Suitable metal complexes for the hole blocking layer include application 08 / 980,986, filed Dec. 1, 1997, application 09 / 883,734, filed Jun. 18, 2001, and April 13, 2001. No. 60 / 283,814 of Japanese Patent Application No. 60 / 283,814, which may include, inter alia, complexes of Os, Ir, Pt and Au, each of which is incorporated herein by reference in its entirety. An example of a metal complex suitable for the hole blocking layer is bis (2- (4,6-difluorophenyl) pyridyl-N, C2 ') iridium (III) picolinate (FIrpic), the structure of which is shown below.

ビス（２−（４，６−ジフルオロフェニル）ピリジル−Ｎ，Ｃ２’）イリジウム（ＩＩＩ）ピコリナート（ＦＩｒｐｉｃ）

Bis (2- (4,6-difluorophenyl) pyridyl-N, C2 ′) iridium (III) picolinate (FIrpic)

［式中、
Ｍは金属原子であり、
ＸはＮ又はＣＸ’（式中、Ｘ’はＨ、Ｃ_１〜Ｃ_２０アルキル、Ｃ_２〜Ｃ_４０モノ−もしくはポリアルケニル、Ｃ_２〜Ｃ_４０モノ−もしくはポリアルキニル、Ｃ_３〜Ｃ_８シクロアルキル、アリール、ヘテロアリール、アラルキル、ヘテロアラルキル、又はハロである）であり、
ＡはＣＨ、ＣＸ’、Ｎ、Ｐ、Ｐ（＝Ｏ）、アリール又はヘテロアリールであり、
Ｒ^１及びＲ^２はそれぞれ独立に、Ｈ、Ｃ_１〜Ｃ_２０アルキル、Ｃ_２〜Ｃ_４０アルケニル、Ｃ_２〜Ｃ_４０アルキニル、Ｃ_３〜Ｃ_８シクロアルキル、アリール、アラルキル、若しくはハロであり、又は
Ｒ^１及びＲ^２は、これらを結合している炭素原子と共に、連結して縮合したＣ_３〜Ｃ_８シクロアルキル又はアリール基を形成し、
Ｒ^３はＨ、Ｃ_１〜Ｃ_２０アルキル、Ｃ_２〜Ｃ_４０アルケニル、Ｃ_２〜Ｃ_４０アルキニル、Ｃ_３〜Ｃ_８シクロアルキル、アリール、アラルキル、又はハロであり、
ｎは１〜５である］
の金属錯体が含まれる。 Suitable metal complexes for the electron blocking layer include those that are relatively difficult to reduce (ie, high LUMO energy levels). Suitable metal complexes include the following formula

[Where:
M is a metal atom,
X is N or CX ′ where X ′ is H, C ₁ -C ₂₀ alkyl, C ₂ -C ₄₀ mono- or polyalkenyl, C ₂ -C ₄₀ mono- or polyalkynyl, C ₃ -C ₈ cyclo Alkyl, aryl, heteroaryl, aralkyl, heteroaralkyl, or halo),
A is CH, CX ′, N, P, P (═O), aryl or heteroaryl,
R ¹ and R ² are each independently H, C ₁ -C ₂₀ alkyl, C ₂ -C ₄₀ alkenyl, C ₂ -C ₄₀ alkynyl, C ₃ -C ₈ cycloalkyl, aryl, aralkyl, or halo, Or R ¹ and R ² together with the carbon atom bonding them together form a fused C ₃ -C ₈ cycloalkyl or aryl group;
R ³ is H, C ₁ -C ₂₀ alkyl, C ₂ -C ₄₀ alkenyl, C ₂ -C ₄₀ alkynyl, C ₃ -C ₈ cycloalkyl, aryl, aralkyl, or halo;
n is 1-5]
These metal complexes are included.

In some preferred embodiments, M is a trivalent metal such as Al or Ga. A that is variable may be preferably CR ³ or N. In some embodiments, R ¹ and R ² are joined to form a fused aromatic ring such as phenyl or pyridyl. A particularly suitable compound in the above formula is gallium (III) tris [2-(((pyrrol-2-yl) methylidene) amino) ethyl] amine (Ga (pma) ₃ ), shown below.

［式中、
Ｍは金属原子であり、
ＸはＮ又はＣＸ’（式中、Ｘ’はＨ、Ｃ_１〜Ｃ_２０アルキル、Ｃ_２〜Ｃ_４０モノ−もしくはポリアルケニル、Ｃ_２〜Ｃ_４０モノ−もしくはポリアルキニル、Ｃ_３〜Ｃ_８シクロアルキル、アリール、ヘテロアリール、アラルキル、ヘテロアラルキル、又はハロである）であり、
Ｒ^１及びＲ^２はそれぞれ独立に、Ｈ、Ｃ_１〜Ｃ_２０アルキル、Ｃ_２〜Ｃ_４０アルケニル、Ｃ_２〜Ｃ_４０アルキニル、Ｃ_３〜Ｃ_８シクロアルキル、アリール、アラルキル、若しくはハロであり、又は
Ｒ^１及びＲ^２は、これらを結合している炭素原子と共に、連結して縮合したＣ_３〜Ｃ_８シクロアルキル又はアリール基を形成し、
Ｒ^３はＨ、Ｃ_１〜Ｃ_２０アルキル、Ｃ_２〜Ｃ_４０アルケニル、Ｃ_２〜Ｃ_４０アルキニル、Ｃ_３〜Ｃ_８シクロアルキル、アリール、アラルキル、又はハロである］
を有していてよい。 Other suitable metal complexes are of the formula

[Where:
M is a metal atom,
X is N or CX ′ where X ′ is H, C ₁ -C ₂₀ alkyl, C ₂ -C ₄₀ mono- or polyalkenyl, C ₂ -C ₄₀ mono- or polyalkynyl, C ₃ -C ₈ cyclo Alkyl, aryl, heteroaryl, aralkyl, heteroaralkyl, or halo),
R ¹ and R ² are each independently H, C ₁ -C ₂₀ alkyl, C ₂ -C ₄₀ alkenyl, C ₂ -C ₄₀ alkynyl, C ₃ -C ₈ cycloalkyl, aryl, aralkyl, or halo, Or R ¹ and R ² together with the carbon atom bonding them together form a fused C ₃ -C ₈ cycloalkyl or aryl group;
R ³ is H, C ₁ -C ₂₀ alkyl, C ₂ -C ₄₀ alkenyl, C ₂ -C ₄₀ alkynyl, C ₃ -C ₈ cycloalkyl, aryl, aralkyl, or halo]
You may have.

As represented throughout the present disclosure, alkyl groups include optionally substituted linear and branched aliphatic groups. Cycloalkyl refers to cyclic alkyl groups, including, for example, cyclohexyl and cyclopentyl, and heterocycloalkyl groups such as pyranyl and furanyl groups. Cycloalkyl groups can be optionally substituted. Alkenyl groups may be unsubstituted or contain at least one carbon-carbon double bond. Alkynyl groups may be unsubstituted or contain at least one carbon-carbon triple bond. Aryl groups are aromatic and substituted aromatic groups having about 3 to about 50 carbon atoms, including, for example, phenyl and naphthyl. A heteroaryl group is an aromatic or substituted aromatic group having from about 3 to about 50 carbon atoms and containing at least one heteroatom. Examples of heteroaryl groups include pyridyl and imidazolyl groups. Aralkyl groups may be unsubstituted or substituted and contain about 3 to about 30 carbon atoms, for example benzyl. Heteroaralkyl includes an aralkyl group containing at least one heteroatom. Halo includes fluoro, chloro, bromo and iodo. Substituted groups can include one or more substituents. Suitable substituents include, for example _H, C 1 _{-C 20 alkyl,} C 2 _{-C 40 alkenyl,} C 2 _{-C 40 alkynyl,} C 3 -C _{8 cycloalkyl,} C 3 -C ₈ heterocycloalkyl, aryl, Heteroaryl, aralkyl, heteroaralkyl, halo, amino, azide, nitro, carboxyl, cyano, aldehyde, alkylcarbonyl, aminocarbonyl, hydroxyl, alkoxy and the like are included. The substituent may be an electron withdrawing group or an electron donating group. As used herein, the term “hetero” is intended to represent a non-carbon atom such as N, O, or S.

Metal complexes suitable for the exciton blocking layer include those having a relatively wide optical gap. Metal complexes suitable for the preparation of the hole blocking layer include high energy absorbers and luminescent materials such as blue luminescent materials. Preferred metal complexes include those where the metal has a closed valence shell (no unpaired electrons). As a result, many of the metal complexes preferred for exciton blocking layer preparation are colorless because their optical gap energy is outside the visible region. Furthermore, complexes having heavy metals are preferred. For example, second and third row transition series heavy metals tend to have larger optical gaps due to stronger ligand fields. Examples of metal complexes suitable for the exciton blocking layer include applications 08 / 980,986 filed on December 1, 1997, 09 / 883,734 filed June 18, 2001, and April 2001. It includes inter alia Os, Ir, Pt and Au complexes, such as those described in the 13 application filed in US 60 / 283,814, each of which is incorporated herein by reference in its entirety. . In some embodiments, suitable metal complexes for the exciton blocking layer include FIrpic, Ga (pma) ₃ and related compounds.

According to some embodiments of the present invention, the device can include a hole transport layer that includes at least one metal complex, and in some embodiments, for example, an organic material, a metal complex, or its An electron blocking layer including both can be included. Suitable organic materials include any organic electron blocking material known in the art such as, for example, triarylamine or benzylidene. In some embodiments, an electron blocking layer is present between the HTL and EL. Thus, the electron blocking layer can be selected such that the HOMO energy level of the electron blocking layer is between the HTL and EL HOMO energy levels. In other embodiments, the HOMO energy level of the electron blocking layer approximates the HOMO energy level of the hole transport layer. For example, the magnitude of the HOMO energy level difference between the electron blocking layer and the hole transport layer may be about 500, 200, 100, 50 meV or less. Examples of metal complexes suitable for the electron blocking layer include complexes having transition metals such as Ga, In, Sn, or Group 8, 9, or 10 transition metals. Other examples of suitable metal complexes include complexes with multidentate ligands. A particularly suitable metal complex is Ga (pma) ₃ .

  Although the metal complexes of HTL described herein can provide charge-transport and / or blocking functions, the metal complexes also have other advantages that increase the thermal stability of the devices of the invention. provide. This is important because OLEDs and similar light emitting devices are exposed to high temperatures for extended periods of time and such exposure is considered a limiting factor in the lifetime of such devices. Thus, devices of the present invention comprising complexes of heavy metals such as second and third series transition metals and fourth and fifth series typical metals are expected to benefit in terms of device lifetime.

  The HOMO and LUMO energy levels of the OLED material can be measured or estimated in several ways known in the art. Two common methods for estimation of HOMO energy levels include solution electrochemical methods such as cyclic voltammetry, and ultraviolet photoelectron spectroscopy (UPS). Two methods for estimation of LUMO levels include solution electrochemistry and backlight emission spectroscopy. As discussed above, by adjusting the HOMO and LUMO energy levels of adjacent layers, the passage of holes and electrons between the two layers can be controlled.

  Cyclic voltammetry is one of the most common methods for measuring the oxidation and reduction potentials of compounds. This technique is well known to those skilled in the art, and the method is briefly described as follows. The test compound is dissolved in a high concentration electrolyte. An electrode is inserted and the voltage is scanned either positively or negatively (depending on whether oxidation or reduction takes place). The current flowing through the cell indicates the presence of a redox reaction. If the voltage scan is then reversed, the redox reaction is reversed. The standard may be an external electrode such as Ag / AgCl or SCE, or an internal electrode such as ferrocene having a known oxidation potential. Since the normal reference electrode is based on water, the latter is often preferred for organic solvents. A useful parameter obtained with cyclic voltammetry is the carrier gap. If both reduction and oxidation are reversible, the energy difference between holes and electrons (ie, the extraction of electrons from HOMO versus the push of electrons into LUMO) can be determined. This value can be used to determine the LUMO energy from a well-defined HOMO energy. Methods for determining the redox potential and reversibility of redox events using cyclic voltammetry are well known in the art.

  UPS is another technique for determining the absolute bond energy in solids. Solution electrochemistry is generally suitable for most compounds and to obtain a relative redox potential, but the measurements taken in the solution phase may differ from those in the solid phase. A preferred method for estimating the HOMO energy in a solid is UPS. This is a photoelectron measurement method in which a solid is irradiated with UV photons. The energy of the photon gradually increases and the electrons generated by the light are observed. When electron emission starts, HOMO energy is provided. The photons at that energy have enough energy to emit electrons from the top of the filled level. UPS provides HOMO energy level values in eV relative to vacuum, which corresponds to the binding energy of electrons.

  Backlight emission can be used to directly estimate the LUMO energy level. This technique involves pre-reduction of the sample and then probing the packing state to estimate the LUMO energy. More specifically, electrons are injected into the material, which then decays to an unoccupied state and emits light. By changing the energy of incoming electrons and the angle of incident light, the electronic structure of the material can be studied. Methods for measuring LUMO energy levels using back light emission are well known to those skilled in the art.

The optical gap value can be determined from the intersection of the normalized absorption and the emission spectrum. For molecules with little structural rearrangement to move from the ground state to the excited state, so that the gap between the absorption and emission λ _max values is relatively small, the crossing energy is the optical gap (0-0 transition energy). ). Therefore, the optical gap roughly corresponds to a HOMO-LUMO gap, and such estimation is appropriate for an ideal system. However, when the shift between the maximum values of absorption and emission is large (Stokes shift), it becomes more difficult to determine the optical gap. For example, considerable errors can occur if there is structural rearrangement in the excited state or if the measured absorption does not represent the lowest energy excited state. Therefore, for the selection of potential exciton blocking materials, it is preferable to use the edge of the absorption band of the material to obtain its optical gap value. In this way, a device layer comprising a material having a higher absorption band energy than that of the adjacent layer can serve as an effective exciton blocking layer. For example, in a device that has a higher energy absorption edge than a material that includes excitons, if the excitons approach the layer, the probability that the excitons are transported to a higher energy material is low. For molecules that emit from triplet excited states, absorption edges are preferred for estimating optical gaps because intersystem crossing results in a very large Stokes shift.

  The light emitting device of the present invention can be fabricated by various techniques well known to those skilled in the art. Small molecule layers, including those consisting of neutral metal complexes, are disclosed in application Ser. No. 08 / 972,156 filed Nov. 17, 1997, which is incorporated herein by reference in its entirety. It can be prepared by solution processing such as vacuum deposition, organic vapor deposition (OVPD), or spin coating. Polymer films can be deposited by spin coating and CVD. Layers of charged compounds, such as salts of charged metal complexes, are disclosed in solution methods such as spin coating or in US Pat. No. 5,554,220, which is hereby incorporated by reference in its entirety. Can be prepared by the OVPD method. Layer deposition is generally not necessarily so, but proceeds in the direction from the anode to the cathode, and the anode is generally placed on the substrate. Also encompassed by the present invention is a method of making such a device comprising depositing a blocking layer comprising a metal complex on an existing layer. Existing layers include any layer designed to contact the blocking layer. In some embodiments, the existing layer may be a light emitting layer or HTL. Apparatuses and techniques for the production thereof are described in literature and, for example, U.S. Pat. Nos. 5,703,436, 5,986,401, 6,013,982, 6,097,147, and 6, 166,489. For devices where the emission is directed substantially outside the bottom of the device (ie, the substrate side), a transparent anode material such as ITO can be used as the base electron. Since the top electrode of such devices need not be transparent, such a top electrode, which is generally a cathode, may be made of a thick reflective metal layer with high electrical conductivity. In contrast, for transparent or top light emitting devices, US Pat. Nos. 5,703,436 and 5,707,745, each of which is incorporated herein by reference in its entirety. A transparent cathode as disclosed in (1) can be used. The top light emitting device may have an opaque and / or reflective substrate such that sufficient light is generated from the top of the device. The device may be completely transparent, emitting from both the top and bottom.

  Transparent cathodes, such as those used in top light emitting devices, preferably have optical transmission properties, such as devices having an optical transmission of at least about 50%, although lower optical transmission may also be used. it can. In some embodiments, the device includes a transparent cathode having optical properties that allow the device to have an optical transmission of at least about 70%, 85%, or more. Transparent cathodes such as those described in US Pat. Nos. 5,703,436 and 5,707,745 generally include a thin layer of a metal such as Mg: Ag having a thickness of, for example, less than about 100 mm. . The Mg: Ag layer can be coated with a transparent and electrically conductive sputter deposited ITO layer. Such cathodes are often referred to as compound cathodes or TOLED (transparent OLED) cathodes. Adjusting the thickness of the Mg: Ag and ITO layers of the compound cathode respectively, both high optical transmission and high electrical conductivity, for example, the electrical conductivity reflected with a total cathode resistivity of about 30-100 Ω / □ Can result in the desired combination. However, some applications allow such relatively low resistivity, but such resistivity requires that the current supplying power to each pixel be conducted through a thin strip of compound cathodes throughout the array. Still somewhat too high for passive matrix array OLED pixels.

  The present invention further provides a method for facilitating hole transport in a light emitting device, wherein the light emitting device preferably comprises a hole transport layer and a light emitting layer, wherein the hole transport layer comprises at least one metal complex. Including methods. According to a preferred embodiment of said method, the device is designed such that the light emitting layer has a HOMO energy level higher than that of the hole transport layer. In some embodiments, the method includes disposing an electron blocking layer between the HTL and the EL, wherein the HOMO energy level of the electron blocking layer has a HOMO energy level between the HTL and EL HOMO energy levels. .

  The present invention further relates to a method for transporting holes in a hole transport layer of a light emitting device, wherein the hole transport layer includes at least one metal complex and includes applying a voltage to the device having the structure. Including methods.

  The structure of a light emitting device is often represented by a sequential enumeration of layer materials separated by slashes. For example, a device having a layer where the anode layer is adjacent to hole transport, it is adjacent to the emissive layer, it is adjacent to the electron blocking layer, and it is adjacent to the cathode layer is anode / HTL / EL / ETL / It can be expressed as a cathode. Such devices of the present invention may include substructures HTL / EL / HBL, HTL / EBL / EL, HTL / EBL / ETL, and others. Some preferred inventive structures include anode / HTL / EL / HBL / ETL / cathode and anode / HTL / EBL / EL / ETL / cathode. In other embodiments, the substructure HTL / EL or HTL each of EL, HTL, and EBL includes at least one metal complex, or none of EL, HTL, or EBL includes only organic molecules. Devices with / EBL / EL are included. Other embodiments include devices that have multiple layers and do not include layers composed solely of organic molecules, or devices that have multiple layers, each layer including at least one metal complex.

  The light emitting device of the present invention can be used for display pixels. In fact, the device of the present invention can be incorporated into any type of display. The display can include a computer monitor, television, personal digital assistant, printer, instrument panel, billboard, etc. In particular, the device of the present invention can be used in heads-up displays because it is substantially transparent when not in use.

  As those skilled in the art will appreciate, many changes and modifications can be made to the preferred embodiment of the present invention without departing from the spirit of the invention. All such modifications are intended to be included within the scope of the present invention.

  Throughout this specification, various groupings are used to conveniently describe the constituent variables of compounds and various groups of related moieties. In particular throughout this specification, each occurrence of such a group shall include all possible sub-combinations of members of the group, including individual members of the group.

  Each of the patents, applications, and publications referred to in this patent specification is hereby incorporated by reference in its entirety.

Synthesis of tris (1-phenylpyrazole-C ² , N ′) cobalt (III) Co (ppz) ₃ ) To a solution of 1-phenylpyrazole (1.0 equiv. Mole, 6.93 mmol) in THF (3 ml). Ethyl magnesium bromide (1.1 equiv. Mole, 7.6 mmol) was added. The reaction mixture was refluxed for 3 hours under an argon atmosphere and then cooled in a dry ice / acetone bath. Then a solution of cobalt (II) bromide (0.5 eq mol, 3.47 mmol) in THF (8 ml) was added slowly to the Grignard reagent. The reaction mixture turned black immediately. The bath was removed and the mixture was stirred for 2 days.

The reaction mixture was transferred to a separatory funnel containing aqueous NH ₄ Cl (10 g / liter, 75 ml) and CH ₂ Cl ₂ (75 ml) and shaken. The resulting thick emulsion was passed through a coarse fritted funnel to help the two layers separate. The organic layer was isolated and the aqueous layer was extracted twice more with CH ₂ Cl ₂ (75 ml). The CH ₂ Cl ₂ solutions were combined, dried over MgSO ₄ , filtered and concentrated under reduced pressure. When hexane was added to the black / yellow concentrate, the product precipitated as a dark yellow solid. By ^{1 H} NMR analysis, the crude product was a mixture of fac isomer and mer isomers, as well as a small amount of impurities was found. Attempts were made to separate the two isomers and impurities by column chromatography using silica gel and 1: 1 CH ₂ Cl ₂ : toluene eluent. Only the fac-type isomer flowed out of the column, but the mer-type isomer stuck to the silica and immediately changed to purple.

Synthesis of tris (1- (4-tolylphenyl) pyrazole-C ² , N ′) cobalt (III) (CoMPPZ) Ligand synthesis (4-tolylphenylpyrazole): 250 ml flask with magnetic stirrer, 4-tolylboro Acid (16 mmol, 2.0 eq), pyrazole (8 mmol, 1.0 eq), anhydrous copper acetate (12 mmol, 1.5 mmol), active 4 活性 molecular sieve 6 g, pyridine (16 mmol, 2.0 eq) ) And 96 ml of dichloromethane were added. The reaction was stirred at ambient temperature under air in a loosely capped flask for 2 days. The reaction mixture was filtered through celite, washed with water, and purified by silica gel chromatography (eluent: ethyl acetate: hexane = 1: 7).

  Complex synthesis: To a solution of 4-tolylpyrazole (1.0 eq mol, 6.93 mmol) in THF (3 ml) was added ethylmagnesium bromide (1.1 eq mol, 7.6 mmol). The reaction mixture was refluxed for 3 hours under an argon atmosphere and then cooled in a dry ice / acetone bath. Then a solution of cobalt (II) bromide (0.5 eq mol, 3.47 mmol) in THF (8 ml) was added slowly to the Grignard reagent. The reaction mixture turned black immediately. The bath was removed and the mixture was stirred for 2 days.

The reaction mixture was transferred to a separatory funnel containing aqueous NH ₄ Cl (10 g / liter, 75 ml) and CH ₂ Cl ₂ (75 ml) and shaken. The resulting thick emulsion was passed through a funnel with a coarse glass filter to help the two layers separate. The organic layer was isolated and the aqueous layer was extracted twice more with CH ₂ Cl ₂ (75 ml). The CH ₂ Cl ₂ solutions were combined, dried over MgSO ₄ , filtered and concentrated under reduced pressure. When hexane was added to the black / yellow concentrate, the product precipitated as a dark yellow solid. ¹ H NMR analysis revealed that the crude product was a mixture of fac and mer isomers, as well as a small amount of impurities. Attempts were made to separate the two isomers and impurities by column chromatography using silica gel and 1: 1 CH ₂ Cl ₂ : toluene eluent. Only the fac-type isomer flowed out of the column, but the mer-type isomer stuck to the silica and immediately changed to purple.

Synthesis of tris (1- (4-methoxyphenyl) pyrazole-C ² , N ′) cobalt (III) (CoMOPPZ) Ligand synthesis (4-methoxyphenylpyrazole): 250 ml flask with magnetic stirrer, 4-methoxyboron Acid (16 mmol, 2.0 eq), pyrazole (8 mmol, 1.0 eq), anhydrous copper acetate (12 mmol, 1.5 mmol), active 4 活性 molecular sieve 6 g, pyridine (16 mmol, 2.0 eq) ), And 96 ml of dichloromethane were added. The reaction was stirred at ambient temperature under air in a loosely capped flask for 2 days. The reaction mixture was filtered through celite, washed with water, and purified by silica gel chromatography (eluent: ethyl acetate: hexane = 1: 7).

  Complex synthesis: To a solution of 4-methoxypyrazole (1.0 eqmol, 6.93 mmol) in THF (3 ml) was added ethylmagnesium bromide (1.1 eqmol, 7.6 mmol). The reaction mixture was refluxed for 3 hours under an argon atmosphere and then cooled in a dry ice / acetone bath. Then a solution of cobalt (II) bromide (0.5 eq mol, 3.47 mmol) in THF (8 ml) was added slowly to the Grignard reagent. The reaction mixture turned black immediately. The bath was removed and the mixture was stirred for 2 days.

The reaction mixture was transferred to a separatory funnel containing aqueous NH ₄ Cl (10 g / liter, 75 ml) and CH ₂ Cl ₂ (75 ml) and shaken. The resulting thick emulsion was passed through a funnel with a coarse glass filter to help the two layers separate. The organic layer was isolated and the aqueous layer was extracted twice more with CH ₂ Cl ₂ (75 ml). The CH ₂ Cl ₂ solutions were combined, dried over MgSO ₄ , filtered and concentrated under reduced pressure. When hexane was added to the black / yellow concentrate, the product precipitated as a dark yellow solid. ¹ H NMR analysis revealed that the crude product was a mixture of fac and mer isomers, as well as a small amount of impurities. Attempts were made to separate the two isomers and impurities by column chromatography using silica gel and 1: 1 CH ₂ Cl ₂ : toluene eluent. Only the fac-type isomer flowed out of the column, but the mer-type isomer stuck to the silica and immediately changed to purple.

Synthesis of tris (1- (4,5-difluorophenyl) pyrazole-C ² , N ′) cobalt (III) (CodFPPZ) Ligand synthesis (4,5-difluorophenylpyrazole): In a 250 ml flask, magnetic stirrer , 4,5-difluoroboric acid (16 mmol, 2.0 eq), pyrazole (8 mmol, 1.0 eq), anhydrous copper acetate (12 mmol, 1.5 mmol), 6 g active molecular sieve 6 g, pyridine ( 16 mmol, 2.0 eq.) And 96 ml of dichloromethane were added. The reaction was stirred at ambient temperature under air in a loosely capped flask for 2 days. The reaction mixture was filtered through celite, washed with water, and purified by silica gel chromatography (eluent: ethyl acetate: hexane = 1: 7).

  Complex synthesis: To a solution of 4,5-difluoropyrazole (1.0 eqmol, 6.93 mmol) in THF (3 ml) was added ethylmagnesium bromide (1.1 eqmol, 7.6 mmol). The reaction mixture was refluxed for 3 hours under an argon atmosphere and then cooled in a dry ice / acetone bath. Then a solution of cobalt (II) bromide (0.5 eq mol, 3.47 mmol) in THF (8 ml) was added slowly to the Grignard reagent. The reaction mixture turned black immediately. The bath was removed and the mixture was stirred for 2 days.

The reaction mixture was transferred to a separatory funnel containing aqueous NH ₄ Cl (10 g / liter, 75 ml) and CH ₂ Cl ₂ (75 ml) and shaken. The resulting thick emulsion was passed through a funnel with a coarse glass filter to help the two layers separate. The organic layer was isolated and the aqueous layer was extracted twice more with CH ₂ Cl ₂ (75 ml). The CH ₂ Cl ₂ solutions were combined, dried over MgSO ₄ , filtered and concentrated under reduced pressure. When hexane was added to the black / yellow concentrate, the product precipitated as a dark yellow solid. ¹ H NMR analysis revealed that the crude product was a mixture of fac and mer isomers, as well as a small amount of impurities. Attempts were made to separate the two isomers and impurities by column chromatography using silica gel and 1: 1 CH ₂ Cl ₂ : toluene eluent. Only the fac-type isomer flowed out of the column, but the mer-type isomer stuck to the silica and immediately changed to purple.

Synthesis of tris (1- (4-fluorophenyl) pyrazole-C ² , N ′) cobalt (III) (COFPPZ) Ligand synthesis (4-fluorophenylpyrazole): 250 ml flask with magnetic stirrer, 4-fluorobor Acid (16 mmol, 2.0 eq), pyrazole (8 mmol, 1.0 eq), anhydrous copper acetate (12 mmol, 1.5 mmol), active 4 活性 molecular sieve 6 g, pyridine (16 mmol, 2.0 eq) ), And 96 ml of dichloromethane were added. The reaction was stirred at ambient temperature under air in a loosely capped flask for 2 days. The reaction mixture was filtered through celite, washed with water, and purified by silica gel chromatography (eluent: ethyl acetate: hexane = 1: 7).

  Complex synthesis: To a solution of 4-fluoropyrazole (1.0 eqmol, 6.93 mmol) in THF (3 ml) was added ethylmagnesium bromide (1.1 eqmol, 7.6 mmol). The reaction mixture was refluxed for 3 hours under an argon atmosphere and then cooled in a dry ice / acetone bath. Then a solution of cobalt (II) bromide (0.5 eq mol, 3.47 mmol) in THF (8 ml) was added slowly to the Grignard reagent. The reaction mixture turned black immediately. The bath was removed and the mixture was stirred for 2 days.

The reaction mixture was transferred to a separatory funnel containing aqueous NH ₄ Cl (10 g / liter, 75 ml) and CH ₂ Cl ₂ (75 ml) and shaken. The resulting thick emulsion was passed through a funnel with a coarse glass filter to help the two layers separate. The organic layer was isolated and the aqueous layer was extracted twice more with CH ₂ Cl ₂ (75 ml). The CH ₂ Cl ₂ solutions were combined, dried over MgSO ₄ , filtered and concentrated under reduced pressure. When hexane was added to the black / yellow concentrate, the product precipitated as a dark yellow solid. ¹ H NMR analysis revealed that the crude product was a mixture of fac and mer isomers, as well as a small amount of impurities. Attempts were made to separate the two isomers and impurities by column chromatography using silica gel and 1: 1 CH ₂ Cl ₂ : toluene eluent. Only the fac-type isomer flowed out of the column, but the mer-type isomer stuck to the silica and immediately changed to purple.

Synthesis of tris (1- (4-tert-butylphenyl) pyrazole-C ² , N ′) cobalt (III) (CoBPPZ) Ligand synthesis (4-tert-phenylpyrazole): In a 250 ml flask, a magnetic stirrer, 4-tert-boric acid (16 mmol, 2.0 eq), pyrazole (8 mmol, 1.0 eq), anhydrous copper acetate (12 mmol, 1.5 mmol), active 4 活性 molecular sieve 6 g, pyridine (16 mmol) 2.0 equivalents), and 96 ml of dichloromethane. The reaction was stirred at ambient temperature under air in a loosely capped flask for 2 days. The reaction mixture was filtered through celite, washed with water, and purified by silica gel chromatography (eluent: ethyl acetate: hexane = 1: 7).

  Complex synthesis: To a solution of 4-tert-pyrazole (1.0 eq mol, 6.93 mmol) in THF (3 ml) was added ethylmagnesium bromide (1.1 eq mol, 7.6 mmol). The reaction mixture was refluxed for 3 hours under an argon atmosphere and then cooled in a dry ice / acetone bath. Then a solution of cobalt (II) bromide (0.5 eq mol, 3.47 mmol) in THF (8 ml) was added slowly to the Grignard reagent. The reaction mixture turned black immediately. The bath was removed and the mixture was stirred for 2 days.

The reaction mixture was transferred to a separatory funnel containing aqueous NH ₄ Cl (10 g / liter, 75 ml) and CH ₂ Cl ₂ (75 ml) and shaken. The resulting thick emulsion was passed through a funnel with a coarse glass filter to help the two layers separate. The organic layer was isolated and the aqueous layer was extracted twice more with CH ₂ Cl ₂ (75 ml). The CH ₂ Cl ₂ solutions were combined, dried over MgSO ₄ , filtered and concentrated under reduced pressure. When hexane was added to the black / yellow concentrate, the product precipitated as a dark yellow solid. ¹ H NMR analysis revealed that the crude product was a mixture of fac and mer isomers, as well as a small amount of impurities. Attempts were made to separate the two isomers and impurities by column chromatography using silica gel and 1: 1 CH ₂ Cl ₂ : toluene eluent. Only the fac-type isomer flowed out of the column, but the mer-type isomer stuck to the silica and immediately changed to purple.

Synthesis of Ga (III) tris [2-((((pyrrol-2-yl) methylidene) amino) ethyl] amine (Ga (pma) ₃ ) Tris (2-aminoethyl) amine (0.720 g, 5 mmol, 10 mL ) To a methanol solution of pyrrole-2-carboxaldehyde (1.430 g, 15 mmol, 100 mL) to prepare the ligand [((((pyrrol-2-yl) methylidene) amino) ethyl] amine. did. The resulting yellow solution was stirred at room temperature for 30 minutes. A methanol solution of gallium (III) nitrate hydrate (1.280 g, 5 mmol, 150 mL) was added to the ligand solution, and the mixture was stirred at room temperature for 30 minutes. The solution was filtered and allowed to crystallize by standing at ambient temperature. The crude product was then sublimed at 235 ° C.

Functional OLEDs were fabricated using the structure ITO / HTL / Alq ₃ / MgAg using the device Co (ppz) ₃ as the HTL of the present invention. These devices had a lower efficiency than the comparative device where the HTL consisted of triarylamine. High efficiency was achieved with these devices when a thin layer of NPD was inserted between the Co (ppz) ₃ layer and the Alq ₃ layer. The HOMO levels of NPD and Co (ppz) ₃ are both similar energies (5.5 eV for NPD and 5.4 eV for Co (ppz) ₃ ). See Figures 13-15.

Devices according to embodiments of the invention Functional OLEDs were fabricated using a Co (ppz) ₃ hole transport layer, a Ga (pma) ₃ electron blocking layer and an Alq ₃ light emitting layer. The operating voltage was about 3.5 V (external brightness at this voltage = Cd / m ² ) and the peak efficiency was greater than 1.2%. See FIGS.

Devices according to embodiments of the invention Functional OLEDs were fabricated using a Co (ppz) ₃ / Ga (pma) ₃ hole transport layer and a doped CBP light emitting layer. Similar devices were also fabricated using NPD hole transport layers. Overall, the Co (ppz) ₃ / Ga (pma) ₃ device performed better than the device using the NPD layer. For Co (ppz) ₃ / Ga (pma) ₃ , the low voltage current is lower and the spectrum does not show blue emission (less than 400 nm). The Co (ppz) ₃ / Ga (pma) ₃ based device had a slightly higher operating voltage and lower quantum efficiency than the NPD based device. Both of these parameters are expected to be improved by device optimization. See FIGS. 11-12.

FIG. 7 compares plots of quantum efficiency versus current density for devices of structure ITO / NPD (500 Å) / Alq ₃ (600 Å) / MgAg and ITO / Co (ppz) ₃ (500 Å) / Alq ₃ (600 Å) / MgAg. . FIG. 3 compares current density versus voltage plots for devices of the structure ITO / NPD (500 Å) / Alq ₃ (600 Å) / MgAg and ITO / Co (ppz) ₃ (500 Å) / Alq ₃ (600 Å) / MgAg. FIG. 7 compares current density versus voltage plots for devices of structure IPO / NPD (500 Å) / Alq ₃ (600 Å) / MgAg and ITO / Co (ppz) ₃ (500 Å) / Alq ₃ (600 Å) / MgAg. FIG. 6 compares plots of quantum efficiency versus current density for devices containing Co (ppz) ₃ . FIG. 6 compares plots of quantum efficiency versus current density for devices containing Co (ppz) ₃ . FIG. 6 compares plots of quantum efficiency versus current density for devices containing Co (ppz) ₃ . FIG. 6 compares current density versus voltage plots for devices containing Co (ppz) ₃ . It is a figure which shows the electronic spectrum of Ga (pma) ₃ . It is a figure which shows the electronic spectrum of Ga (pma) ₃ . FIG. 4 is a plot of current density versus voltage for a device having the structure ITO / Co (ppz) ₃ (400 Å) / Ga (pma) ₃ (100 Å) / Alq ₃ (500 Å) / MgAg (1000 Å) / Ag. FIG. 4 is a plot of luminance versus voltage for devices of the structure ITO / Co (ppz) ₃ (400 Å) / Ga (pma) ₃ (100 Å) / Alq ₃ (500 Å) / MgAg (1000 Å) / Ag FIG. 4 is a plot of external quantum efficiency versus voltage for devices of the structure ITO / Co (ppz) ₃ (400 Å) / Ga (pma) ₃ (100 Å) / Alq ₃ (500 Å) / MgAg (1000 Å) / Ag. FIG. 6 is a plot of external quantum efficiency versus current density for devices of the structure ITO / Co (ppz) ₃ (400 Å) / Ga (pma) ₃ (100 Å) / Alq ₃ (500 Å) / MgAg (1000 Å) / Ag. FIG. 6 is a plot of current density versus voltage for a device with the structure ITO / HTL (500 Å) / CBP: Irppy (6%) (200 Å) / BCP (150 Å) Alq ₃ (200 Å) / LiF / Al. FIG. 5 is a plot of luminance versus voltage for a device with the structure ITO / HTL (500 Å) / CBP: Irppy (6%) (200 Å) / BCP (150 Å) Alq ₃ (200 Å) / LiF / Al. FIG. 6 is a plot of quantum efficiency versus current density for a device having the structure ITO / HTL (500 Å) / CBP: Irppy (6%) (200 Å) / BCP (150 Å) Alq ₃ (200 Å) / LiF / Al. FIG. 6 shows a plot of the emission spectrum of a device having the structure ITO / HTL (500 Å) / CBP: Irppy (6%) (200 Å) / BCP (150 Å) Alq ₃ (200 Å) / LiF / Al. FIG. 6 is a plot of current versus voltage for devices of the structure ITO / Co (ppz) ₃ (400 Å) / NPD (100 Å) / Alq ₃ (500 Å) / Mg: Ag (1000 Å) / Ag (400 Å). FIG. 4 is a plot of luminance versus voltage for devices of the structure ITO / Co (ppz) ₃ (400 Å) / NPD (100 Å) / Alq ₃ (500 Å) / Mg: Ag (1000 Å) / Ag (400 Å). FIG. 4 is a plot of quantum efficiency versus voltage for a device of the structure ITO / Co (ppz) ₃ (400 Å) / NPD (100 Å) / Alq ₃ (500 Å) / Mg: Ag (1000 Å) / Ag (400 Å). FIG. 4 is a plot of quantum efficiency versus current density for a device of the structure ITO / Co (ppz) ₃ (400 Å) / NPD (100 Å) / Alq ₃ (500 Å) / Mg: Ag (1000 Å) / Ag (400 Å). It is a figure which shows some hole transport materials. FIG. 3 shows several metal complexes suitable for the layers of the device of the present invention. It is a figure which shows the aspect of the movement of a carrier. It is a figure which shows the chemical synthesis of the metal complex suitable for the device of this invention. It is a figure which shows the absorption spectrum of the some Co compound suitable for the device of this invention. It is a figure which shows the cyclic voltammogram of Co complex suitable for the device of this invention. It is a figure which illustrates the characteristic of the device containing Co compound. It is a figure which illustrates the characteristic of the device containing Co (ppz) ₃ and an NPD electron blocking layer. It is a figure which illustrates the photophysical characteristic of Ga (pma) ₃ . It is a figure which illustrates the characteristic of the device which does not contain the layer only of an organic thing. It is a figure which illustrates the characteristic of the device which does not contain the layer only of an organic thing. It is a figure which shows the comparison with the characteristic of the device containing NPD, and the characteristic of the device containing Co and Ga metal complex instead of NPD.

Claims (76)

A light emitting device comprising an anode, a hole transport layer, a light emitting layer, and a cathode in this order , wherein the hole transport layer comprises at least one metal complex, and the metal complex is represented by the formula I or II:

[Wherein, M ′ and M ′ ″ are each independently a metal atom,
R ₁₀ , R ₁₃ , R ₂₀ and R ₂₁ are each independently N or C;
R ₁₁ and R ₁₂ are each independently N or C;
Ring systems A, B, G, K and L are each independently a monocyclic, bicyclic or tricyclic fused aliphatic or aromatic ring system which may optionally contain up to 5 heteroatoms. ,
Z is _C 1 -C _{6 alkyl,} C 2 -C ₈ mono - and or polyalkynyl, or a bond, - or _polyalkenyl, C 2 -C ₈ mono
Q is BH, N or CH]
A light emitting device having one of the following: The light emitting device of claim 1, wherein the metal complex has Formula I. The light-emitting device according to claim 2, wherein the metal complex has the formula I, and the ring system A and the ring system B are each monocyclic. 4. A light emitting device according to claim 3, wherein the metal complex has the formula I, the ring system A is a 5-membered heteroaryl monocycle and the ring system B is a 6-membered aryl or heteroaryl monocycle. R _I0 and _{R 11} is _N, the light emitting device according to claim 4 _{R 13} is C. The light-emitting device according to claim 4, wherein ring A forms pyrazole. The light-emitting device according to claim 4, wherein ring B forms phenyl. The light emitting device according to claim ¹ , wherein the metal is a metal of d ⁰ , d ¹ , d ² , d ³ , d ⁴ , d ^5, or d ⁶ . The light emitting device according to any one of claims 1 to 7, wherein M 'is a transition metal. The light emitting device according to claim 1, wherein M ′ is Fe, Co, Ru, Pd, Os, or Ir. The light emitting device according to claim 1, wherein M ′ is Fe or Co. The light emitting device according to claim 1, wherein M ′ is Co. The light emitting device according to claim 1, wherein M ′ is Fe. The light emitting device according to claim 1, wherein the metal complex is Co (ppz) ₃ . The light emitting device of claim 1 wherein the metal complex has the formula II. The light-emitting device according to claim 1, wherein the metal complex has the formula II and the ring systems G, K and L are each a 5-membered or 6-membered monocycle. The light-emitting device according to claim 16, wherein the ring systems G, K and L are each a 5-membered heteroaryl monocycle. The light-emitting device according to claim 17, wherein R ₂₁ and R ₂₂ are each N. 19. A light emitting device according to claim 18, wherein the ring systems G, K and L each form a pyrazole. The light-emitting device according to claim 15, wherein M ′ ″ is a metal of d ⁵ , d ⁶ , d ² , or d ³ . The light-emitting device according to claim 15, wherein M ″ ″ is a transition metal. The light-emitting device according to claim 15, wherein M ″ ″ is Fe, Co, Ru, Pd, Os, or Ir. The light-emitting device according to claim 15, wherein M ″ ″ is Fe or Co. The light-emitting device according to claim 15, wherein M ″ ″ is Fe. The light emitting device according to claim 15, wherein the metal complex is FeTp ′ ₂ . The light emitting device of claim 1 further comprising an electron blocking layer. 27. The light emitting device of claim 26, wherein the electron blocking layer comprises an organic electron blocking material. 28. The light emitting device of claim 27, wherein the organic electron blocking material is selected from triarylamine or benzylene. The light emitting device according to any one of claims 26 to 28, wherein the electron blocking layer includes a metal complex. 30. The light emitting device of claim 29, wherein the electron blocking layer consists essentially of the metal complex. 30. The light emitting device of claim 29, wherein the electron blocking layer comprises a matrix doped with the metal complex. 30. The light emitting device of claim 29, wherein the electron blocking layer has a HOMO energy level that approximates a HOMO energy level of the hole transport layer. 30. The light emitting device of claim 29, wherein the electron blocking layer has a HOMO energy level that is higher than a HOMO energy level of the hole transport layer. 32. The light emitting device according to any one of claims 29 to 31, wherein the metal complex of the electron blocking layer comprises a metal selected from Ga, In, Sn, or a group 8, 9, or 10 transition metal. The light emitting device according to any one of claims 29 to 31, wherein the metal complex of the electron blocking layer contains Ga. The light emitting device according to any one of claims 29 to 31, wherein the metal complex of the electron blocking layer contains a polydentate ligand. 37. The light emitting device of claim 36, wherein the multidentate ligand has a bridging atom selected from N and P. The light-emitting device according to claim 36, wherein the multidentate ligand has a mesityl bridging moiety. 37. The light emitting device of claim 36, wherein the polydentate ligand comprises up to three monocyclic, bicyclic, or tricyclic heteroaromatic moieties. A compound having the following formula:

[Where:
M is a metal atom,
X is N or CX ′ where X ′ is H, C ₁ -C ₂₀ alkyl, C ₂ -C ₄₀ mono- or polyalkenyl, C ₂ -C ₄₀ mono- or polyalkynyl, C ₃ -C ₈ cyclo Alkyl, aryl, heteroaryl, aralkyl, heteroaralkyl, or halo),
A is CH, CX ′, N, P, P (═O), aryl or heteroaryl,
Are R ¹ and R ² each independently H, C ₁ -C ₂₀ alkyl, C ₂ -C ₄₀ alkenyl, C ₂ -C ₄₀ alkynyl, C ₃ -C ₈ cycloalkyl, aryl, aralkyl, or halo? Or R ¹ and R ² together with the carbon atom bonded to them, form a C ₃ -C ₈ cycloalkyl or aryl group linked together and condensed,
R ³ is H, C ₁ -C ₂₀ alkyl, C ₂ -C ₄₀ alkenyl, C ₂ -C ₄₀ alkynyl, C ₃ -C ₈ cycloalkyl, aryl, aralkyl, or halo;
n is 1-5]
The light emitting device of claim 1, further comprising an electron blocking layer comprising: M is a trivalent metal atom,
X is CH or N;
A is N or 1,3,5-phenyl;
R ¹ and R ² are each H, or R ¹ and R ² together with the carbon atom to which they are attached are linked to form a phenyl group
R ³ is H;
41. The light emitting device according to claim 40, wherein n is 1 or 2. 42. The light emitting device according to claim 40 or 41, wherein M is Ga. 41. A light emitting device according to claim 40, wherein the electron blocking layer comprises Ga (pma) ₃ . 41. The light emitting device according to claim 40, wherein the metal complex of the hole transport layer is Co (ppz) ₃ . The light emitting device of claim 40 wherein the metal complex of the HTL is FeTp _'2. The light-emitting device of claim 1 comprising a hole transport layer, a light-emitting layer, and a blocking layer,
The hole transport layer has a first HOMO energy, the hole transport layer comprises at least one metal complex, and the light emitting layer comprises at least one material capable of transporting electrons, the material comprising: The light emitting device of claim 1, wherein the light emitting device has a second HOMO energy and the blocking layer comprises a material having a HOMO energy that is between the first and second HOMO energies. 47. The device of claim 46, wherein the blocking layer is between the hole transport layer and the light emitting layer. The device of claim 46, wherein the blocking layer comprises an organic electron blocking material. 49. The light emitting device of claim 48, wherein the organic electron blocking material is selected from triarylamine or benzylene. The light emitting device of claim 46, wherein the electron blocking layer comprises a metal complex. A method for promoting hole transport in a light emitting device according to claim 1, wherein the light emitting device comprises a hole transport layer and a light emitting layer,
The hole transport layer comprises at least one metal complex and has a first HOMO energy;
The light emitting layer includes at least one material capable of transporting electrons, the material having a second HOMO energy higher than the HOMO energy of the hole transport layer;
The method includes disposing a blocking layer between the hole transport layer and the light emitting layer, the blocking layer having a HOMO energy level that is between the first and second HOMO energies. Including materials,
Method. The method according to claim 51 wherein the metal complex of the hole transport layer is Co _{(ppz) 3} or FeTp _'2. 53. A method according to claim 51 or 52, wherein the blocking layer comprises at least one metal complex. The metal complex of the blocking layer has the following formula:

[Where:
M is a metal atom,
X is N or CX ′ where X ′ is H, C ₁ -C ₂₀ alkyl, C ₂ -C ₄₀ mono- or polyalkenyl, C ₂ -C ₄₀ mono- or polyalkynyl, C ₃ -C ₈ cyclo Alkyl, aryl, heteroaryl, aralkyl, heteroaralkyl, or halo),
A is CH, CX ′, N, P, P (═O), aryl or heteroaryl,
Are R ¹ and R ² each independently H, C ₁ -C ₂₀ alkyl, C ₂ -C ₄₀ alkenyl, C ₂ -C ₄₀ alkynyl, C ₃ -C ₈ cycloalkyl, aryl, aralkyl, or halo? Or R ¹ and R ² together with the carbon atom bonded to them, form a C ₃ -C ₈ cycloalkyl or aryl group linked together and condensed,
R ³ is H, C ₁ -C ₂₀ alkyl, C ₂ -C ₄₀ alkenyl, C ₂ -C ₄₀ alkynyl, C ₃ -C ₈ cycloalkyl, aryl, aralkyl, or halo;
n is 1-5]
54. The method of claim 53, wherein the compound is 54. The method of claim 53, wherein the metal complex of the blocking layer is Ga (pma) ₃ . The hole transport layer comprises a Co _{(ppz) 3} or FeTp _'2, The method of claim 51 wherein the blocking layer comprises Ga _{(pma) 3.} A method for making a light emitting device according to claim 1, comprising disposing the hole transport layer in electrical contact with the light emitting layer, wherein the hole transport layer is a compound of formula I or II:

[Where:
M ′ and M ′ ″ are each independently a metal atom,
R ₁₀ , R ₁₃ , R ₂₀ and R ₂₁ are each independently N or C;
R ₁₁ and R ₁₂ are each independently N or C;
Ring systems A, B, G, K and L are each independently a monocyclic, bicyclic or tricyclic fused aliphatic or aromatic ring system which may optionally contain up to 5 heteroatoms. ,
Z is _C 1 -C _{6 alkyl,} C 2 -C ₈ mono - and or polyalkynyl, or a bond, - or _polyalkenyl, C 2 -C ₈ mono
Q is BH, N or CH]
Including a method. 58. The method of claim 57, wherein the light emitting device further comprises an electron blocking layer. The electron blocking layer has the following formula:

[Where:
M is a metal atom,
X is N or CX ′ where X ′ is H, C ₁ -C ₂₀ alkyl, C ₂ -C ₄₀ mono- or polyalkenyl, C ₂ -C ₄₀ mono- or polyalkynyl, C ₃ -C ₈ cyclo Alkyl, aryl, heteroaryl, aralkyl, heteroaralkyl, or halo),
A is CH, CX ′, N, P, P (═O), aryl or heteroaryl,
Are R ¹ and R ² each independently H, C ₁ -C ₂₀ alkyl, C ₂ -C ₄₀ alkenyl, C ₂ -C ₄₀ alkynyl, C ₃ -C ₈ cycloalkyl, aryl, aralkyl, or halo? Or R ¹ and R ² together with the carbon atom bonded to them, form a C ₃ -C ₈ cycloalkyl or aryl group linked together and condensed,
R ³ is H, C ₁ -C ₂₀ alkyl, C ₂ -C ₄₀ alkenyl, C ₂ -C ₄₀ alkynyl, C ₃ -C ₈ cycloalkyl, aryl, aralkyl, or halo;
n is 1-5]
59. The method of claim 58, comprising a compound having: 59. The method of claim 58, wherein the electron blocking layer comprises Ga (pma) ₃ . The method of claim 57 wherein said compound is Co _{(ppz) 3} or FeTp _'2. 58. The method of claim 57, wherein the compound is Co (ppz) ₃ . A pixel comprising the light emitting device according to claim 1. A pixel comprising the light emitting device according to claim 14. A pixel comprising the light emitting device according to claim 25. 41. A pixel comprising the light emitting device according to claim 40. 47. A pixel comprising the light emitting device according to claim 46. An electronic display comprising the light emitting device according to claim 1. An electronic display comprising the light emitting device according to claim 14. An electronic display comprising the light emitting device according to claim 25. 41. An electronic display comprising the light emitting device according to claim 40. 47. An electronic display comprising the light emitting device according to claim 46. The light emitting device of claim 1, wherein the metal complex is coordinately saturated. The light emitting device according to claim 1, wherein the metal complex has a coordination number of 6. The light emitting device according to claim 1, wherein the metal complex has a coordination number of 4. The light emitting device of claim 9, wherein the transition metal is a first series of transition metals.

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